Add growth weekly report policy

What does this MR do and why?

Related to: gitlab-org/growth/team-tasks#661 (closed)

Creates a policy executed weekly (each Monday 3:00am) to generate a report for Growth section (delivered issues, in progress, blockers).

Expected impact & dry-runs

Here is the result of dry-run: https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/4850743003

Action items

• If adding environment variables for reactive processors, update config/triage-web.yaml and .gitlab/ci/triage-web.yml
• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable - not - it's Growth group only change) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review